Magnetic structure



Feb. 14, 1950 C, E, BAZLEY 2,497,652

` MAGNETIC STRUTURE F1166. NOV. 18, 1947 b @A my yMie. Attorney Patented Feb. 14, 1950 MAGNETIC STRUCTURE Carl E. Bailey, Schenectady, N. Y., assignor to General Electric Company,

New York a corporation of Application November 18, 1947, Serial No. 786,708 3 Claims. (Cl. 175-21) My invention relates to magnetic structures,

and more particularly to electromagnets of the variable reluctance type, It is a general object of my invention to provide new and novel means, readily adjustable, for controilably varying the reluctance of a magnetic structure.

It is a more specific object of my invention to provide a magnetizable structure oi variable ren luctance which is simple and inexpensive to manuiacture and durable and reliable in operation'.

My invention is particularly applicable to ma netizable structures for electromagnetic control devices, suoli as relays and the like. My n" and improved structure finds particular apc cation in connection 'with elec flagnetie t delay relays wherein Jarlatloz c. .e iustment may "oe util s contro?. t se time eleqa s ment of the My invention ltse Le fully orarie"u stood and its various corsets and advantages ther appreciated by referring now to the follow lng detailed speciiieation tal: conjunctic i. with the accompanying drawing, which Fig. is cross sectional side view an electromagnetic time delay relay illustrating one embod'ln ment of my invention; and Fig. 2 is an exploded perspective View oi a portion oi the magnetizable frame oi the relay at l, showing in detail the means for varying the magnetic reluctance of that portion of the frame.

Referring now to the drawing, the electromagnetic time delay relay which I have shown for the purpose `oz? illustrating one embodiment of my invention comprises a base l formed of a suitable molded plastic insulating material and l having mounted thereon a pair of fixed contacts 2. The contacts 2 are connected by electric conducting strap 3 to a pair of terminal connectors t disposed on opposite ends of the base l. Carried also upon the base l is a housing 5 formed of insulating material and provided with a cover plate E of insulating material. The housing 5 and the cover 6 may suitably be connected to thebase -I by a plurality of bolts (not shown) passing through the cover 6 and threaded into tapped inserts (not shown) in the base l. The insulating cover is provided with a large rectangular .aperture within which is mounted a, block 'l of electric conducting material. The block l is xedly connected to the insulating cover 6 by bolts or the like (not shown), and is provided with a pair of cylindrical apertures in parallel spaced relation. Within the apertures in the electric conducting blocls l are positioned upper ends by a pair of a pair of magnetizabie core members 8. magnetizable core members conducting block l and are The t project above the surrounded at their energizing windings or coils A generally irl-shaped frame r" the relay is completed by magnetically linking of the core members fl through a netizahle blocks l@ f tion. The mago sliding move` an upper in plastic lnsnlat head il and s- -smalle relay ooi provided with enlar for a purpose which will hereinafter.,

The relay shown at l. includes also a l armature l5 formed of magnetizable material a carrying a pair of electrically connected movable bridging contacts arranged for cooperation with the fixed contacts At opposite ends of the armature l5 are a pair brackets fixed to the armature and carrying a pair of upright guide rods i8. Each rod is mounted for slid ing movement through a pair of aligned apertures the insulating cover 6 and the insulating head member il. fr pair of helical biasing compression springs it are disposed on the rods lll between the insulating cover l? and the armature bracket ll. The springs IS retain the armature I5 normally in a dropped out position with the contacts 2 and I6 in engagement.

Referring now more particularly to Fig. 2, the magnetzable blocks lll forming the upper con-1 necting portion of the U-shaped relay frame be-d tween the upper ends of the coil cores G are of flat rectangular shape and are disposed in endto-end relation Within the rectangular recess (Fig. l) in the lower side of the insulating head ll. The rectangular recess lla is longer than the total length of the abutting blocks it, thereby to provide for sliding movement and separation of the blocks at their contiguous end surfaces. The blocks I@ are transversely' slotted across their opposite end surfaces, as at lue, and.

in these slots are positioned a pair oi .arched leaf springs 20. The leaf springs 20 are thus interposed between opposite ends of the blocks I and ends of the rectangular recess lia, thereby to bias the magnetizable blocks w into end-toend abutting engagement.

In order to force the magnetizable blocks il! apart and to retain the blocks in 'variable spaced apart relation against their bias, I provide a tapered boit 2l formed of non-magnetizable material, such as brass or the like. The tapered bolt 2l is threaded into a tapped and tapered elliptical hole 22 formed partially in each oi the magnetizable blocks I0. The tapped hole 22 is formed by oppositely conically recessing and threading the blocks Il) along a center line which lies parallel to and equally spaced from the contiguous end surfaces of the blocks when the blocks are held at or slightly beyond their position of maximum separation. This tapping operation is conveniently carried out by' interpcslng between the blocks a shim having a thickness equal to or slightly greater than the distance oi maximum separation of the blocks, and then tapping a tapered hole having its center line at the center of the sim. Such a shim may be of the order of 5 to 7 mils in thickness. The bolt 2i thus serves as an adjustable wedge, engaging the blocks i0 along onlythe recessed or tapped portion of their 1contiguous surfaces, and arranged either to permit abutting engagement or the blocks or to retain the blocks in spaced apart relation against their bias.` The extent to which the blocks are spaced apart is determined by the extent to `which the tapered bolt 2li is screwed down into the tapped and tapered hole 22. The spacing between the blocks determines the magnetic reluctance of the relay frame.

In order to lock the non-magnetizable bolt 2l in position and thus nx the adjustment of the magnetlzable blocks lll, the bolt 2i is provided with a control knob or head 223 which is suitably formed of a molded plastic insulating material and arranged for interlocking engagement with the bolt head it. The knob 23 is of larger diameter than the bolt 2l and is provided around its periphery with a plurality of flutes 23a, preferably cylindrical and having a radius of curvature corresponding to the radius of curvature of the bolt head i4 (Fig. l). The bolt 2i and the bolt i3 carrying the head i4 are so positioned that -when the bolt i3 is screwed clown tightly, the enlarged head l5 fits into one of the flutes 23a and locks the bolt 2i against turning.

In operation, it will be understood that dropout of the relay is delayed for an appreciable time interval by the jacket l of electric conducting material surrounding the lower portions of the coil cores 8. The precise length of the drop-out interval is controllable by varying the reluctance oi the magnetic circuit of the relay. This reluctance variation is accomplished by adjustably positioning the magnetlzable .blocks l0 by means of the non-magnetizable tapered bolt 2 l.

When it is desired to change the reluctance of the relay frame, the bolt I3 is rst withdrawn until the enlarged head il is clear of engagement with the control knob 2t. Loosening or the bolt I3 releases the clamping pressure upon one of the blocks lli and allows sliding movement of this one block. The bolt i2 is then loosened to permit movement of the other block i0. Next, the control knob 23 and the bolt 2i are turned to position the blocks lllY as desired. The

4 bolts l2 and Il are then tightened to clamp the block i0 in position, the head l! and the bolt ll simultaneously locking the tapered bolt :i in position.

It will, of course, be understood that a limited amount of reluctance adjustment may be carried out without looseningthe bolt i2. In this case, only one of the blocks i0 is movable within the head il, so that reluctance variation may be eected only within the limits of movement of the one block it. Indeed, if desired, the spring 2@ in the block iii which is clamped by the bolt i2 may be omitted and the bolt i2 left tight in clamping position at all times. In this mode of operation it is desirable, in order to permit a maximum oi adjusting movement, that the block l@ clamped by the bolt i2 be clamped in its position of maximum retraction, that is, against the end oi the recess i la.

While I have shown and described only a preferred embodiment of my invention by way of illustration, it is evident that manymodications will occur to those skilled in the art, and I therefore intend in the appended claims to cover all such modidcations as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

l. In a magnetic structure of variable magnetic reluctance, a non-magnetizable base, a pair of relatively movable magnetizable members slidably mounted on said base, spring means interposed between each of said members and said base to bias said members into abutting engagement along a pair of contiguous surfaces, said members being conically tapped along a center line lying parallel to and equally spaced from said surfaces when said members are spaced apart, thereby jointly to provide a tapered boltreceiving aperture, and a tap-ered bolt oi nonmagnetizable material positioned in said enern ture and arranged to separate said members against their bias, thereby to control the reluctance of said structure.

2. In a magnetic structure of variable magnetic reluctance, a non-magnetizable base having a rectangular recess therein, a pair or blocks of magnetizable material mounted for relative :movementl in said recess, spring means interposed between at least one of said blocks and said base at one end of said recess to bias said blocks into abutting endtoendl relation, said blocks being conically tapped along a center line lying parallel to and equally spaced from the abutting end surfaces of said blocks when said blocks are spaced apart. thereby to provide a tapered bolt-receiving aperture, and a tapered bolt of non-magnetizable material threaded into said aperture and adjustably positionable to permit engagement of said blocks or to retain said blocks in variable spaced apart relation.

3. In a magnetic structure of variable magnetic reluctance, a base, a pair of relatively movable magnetizable members slldably mounted upon said base, spring means engaging said base and said members and arranged to bias saic' members into abutting engagement along a pair of contiguous surfaces, said members being conically tapped along a center line lying parallel tc and equally spaced from said surfaces when saic members are spaced apart thereby jointly t: provide a tapered bolt-receiving aperture, and e tapered threaded bolt of non-magnetizable material positioned in said aperture in engagemem with said magnetizable members and arrange:

5 6 to separate said members against their bias. thereby to control the reluctance of said strucf UNITED STATES PArE'NTS ture, Number v Name Date CARL E. BAZLEY- 1,976,584 Stickney Oct. 9, 1934 5 2,055,175 Franz Sept. 22, 1936 REFERENCES CITED The following references are of record in the file of this patent: 

